Women who carry two key gene mutations that significantly raise their risk of breast and ovarian cancer can nearly eliminate that risk by having preventive mastectomies or surgery to remove their ovaries, new research finds.
Doctors say the results of the study underscore the importance for all women with a family history of breast or ovarian cancer to get tested for the BRCA1/2 gene mutations.
For the new study, researchers from the University of Pennsylvania School of Medicine looked at almost 2,500 women with BRCA1 or BRCA2 mutations. The women were followed up until the end of 2009.
Among 247 women with the genes who decided to undergo preventive mastectomies, none developed breast cancer during three years of follow-up. That compares to 98 women of 1,372 who didn't have the surgery (7 per cent) who were diagnosed with breast cancer over a similar follow-up period.
The study also looked at gene mutation carriers who decided to have their ovaries removed to reduce their cancer risk. Among them, no ovarian cancer was seen during six years of follow-up, compared to three per cent of gene mutation carriers who didn't have the surgery.
Women who had their ovaries and fallopian tubes removed also had a lower risk of developing breast cancer, as well as a lower risk of death from any cause.
The research appears in JAMA, the Journal of the American Medical Association.
It's estimated that about 10 to 20 per cent of breast and ovarian cancers are due to BRCA1 or BRCA2 genes. It's also estimated that about 15 to 40 per cent of women who have the BRCA1 or BRCA2 mutations will develop ovarian cancer, compared to just 1.4 per cent of women among the general population.
"This is the first study to prove women survive longer with these preventive surgeries and shows the importance of genetic testing when there is a family history of early breast or ovarian cancer," writes breast cancer researcher Dr. Virginia Kaklamani, in an accompanying editorial in JAMA.
Kaklamani and editorial coauthor, Dr. Laura Esserman, from the University of California, San Francisco, say the finding reinforce the assertion that all women with a family history of ovarian cancer or breast cancer be genetically tested.
"Testing should not start with the oncologists. That's when patients already have breast cancer. The primary care doctors and gynecologists are the ones who should evaluate patients and offer them genetic counseling," they write.
Even women diagnosed with breast or ovarian cancer can still benefit from genetic testing, they write, because the gene mutation significantly increases the risk of a second cancer diagnosis.
Kaklamani and Esserman also encourage all women diagnosed with the gene mutations to consider preventive surgery, rather than increased surveillance. They note that surveillance is not prevention, and that because ovarian cancer is notoriously difficult to diagnose, screening has limited value.
They note that ovarian surgery is relatively low risk, while the cosmetic options for women getting mastectomies have greatly improved.
